Invia reflex raman confocal multilaser spectrometer

The Raman and SERS spectra were recorded using a Renishaw™ inVia Reflex Raman confocal multilaser spectrometer having a spectral resolution of 0.5 cm⁻¹. The wavelength calibration was performed using an internal silicon reference. All the spectra presented in this paper were acquired using a 100× (N.A = 0.85) objective. A 785 nm diode laser (Renishaw, UK) was used for excitation. The laser power (measured at the sample surface) was ~65 mW for Raman measurements and ~1.95 mW for SERS ones. The acquisition time was set to 10 s. The spectrograph was equipped with a 1200 lines/mm grating and a charge coupled device camera (CCD). WiRE 4.2 software (Renishaw plc, Gloucestershire, UK) was used for data collection and spectral pre-processing, including cosmic ray removal and baseline correction. The latter one was applied to all spectra in order to eliminate the fluorescence background. Each spectrum was an average of 30 spectral acquisitions from different positions of the whole dried sample area.

The Raman spectra were recorded using a Renishaw inVia Reflex Raman confocal multilaser spectrometer possessing a spectral resolution of 1 cm⁻¹. The wavelength calibration was performed using an internal silicon reference. All Raman spectra were acquired using a 50× (NA = 0.75) Leica objective. A 785 nm diode laser (Renishaw, Gloucestershire, UK) was used for excitation. The laser power (measured at the sample surface) was ~63 mW. The exposure time was set to 1 s, and 20 accumulations were used for each measurement.
The spectrograph was equipped with a 600 lines/mm grating and a charge-coupled device camera (CCD). WiRE 4.2 software (Renishaw plc, Gloucestershire, UK) was used for data collection and spectral preprocessing, including cosmic ray removal and baseline correction. The latter was applied to all spectra to eliminate the fluorescence background. Carbon dots spectrum represents an average of 25 spectral acquisitions from different positions of the whole dried ring sample area.